Slip and falls continue to be one of the leading causes of work-related injuries. The reduction of these injuries is dependent upon improved identification of slippery conditions and the design of proper shoes and floors for various environments. The long-term goal of this research project is to reduce injuries due to slips and falls in the workplace through the development of a computational model that predicts the coefficient of friction (COF) of the shoe-floor-contaminant interface. The model will be based upon: 1) micro-level properties of the shoe-floor-contaminant interface (material and surface characteristics along with lubrication properties), and 2) macro- level designs of the shoe (i.e. tread and shape) and floor. The micro-level model will include measurements of properties of shoes, floors and contaminants that will be combined in a computational model based upon fundamental tribological relationships. The macro-level model will incorporate the micro-level model into a finite element representation of the shoe-floor interface. Micro-level model predictions will be compared to current tribological COF testing and macro-level model predictions will be compared to currently used shoe-floor interface slip resistance testing devices. The model predictions will also be compared to actual human slips and falls during gait to determine the efficacy in predicting slips and/or falls. If successful, this model will be able to be used in the evaluation and, more importantly, the design of shoes and floors for various environments. PUBLIC HEALTH RELEVANCE: Slip and falls continue to be one of the leading causes of work-related injuries. The long-term goal of this research is to reduce injuries due to slips and falls in the workplace. The objective is to develop a computational model of friction that will relate directly to slip based upon: 1) micro- level properties of the shoe-floor-contaminant interface, and 2) macro-level designs of the shoe and floor. The micro-level model will be validated using tribological COF testing. The macro- level model will be compared to slip resistance testers, including a new robotic-based High Payload Precision Slipmeter (HPPS) developed by the investigators. The macro-level model outputs will also be compared to actual human slips and falls during gait to determine the efficacy in predicting slips and/or falls. Thus, the three specific aims are: 1) Develop and validate a micro-level tribological model of the shoe-floor-contaminant interface based upon material properties, surface microstructure and contaminant characteristics. 2) Develop a macro-level model of the shoe-floor-contaminant interface that incorporates the micro-level model and macro-level shape and asperities (i.e. tread). 3) Conduct human slipping experiments to validate the macro-model with actual slip/fall events. If successful, this model will be able to be used in the evaluation and, more importantly, the design of shoes and floors for various environments.